Compute a reasonable effect size measure for the data in Exercise 20.1. There are probably several different measures that you could come up with, so you should chose one that will give your reader a real sense of the role played by lesions to the amygdala.

I frequently ask you to use SPSS or R to solve a problem. You should have no problem with SPSS if you stick with the “Legacy” analyses. You should be able to use R by modifying the code that I give on the Web page for this chapter: http://www.uvm .edu/~dhowell/fundamentals9/Supplements/Chapter20R.html Exercise 20.1

Kapp, Frysinger, Gallagher, and Hazelton (1979) have demonstrated that lesions in the amygdala can reduce certain responses commonly associated with fear (e.g., decreases in heart rate).

If fear is really reduced by the lesion, it should be more difficult to train an avoidance response in those animals because the aversiveness of the stimulus will consequently be reduced. Assume two groups of rabbits: One group has lesions in the amygdala, and the other is an untreated control group. The following data represent the number of trials to learn an avoidance response for each animal.

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Group with Lesions Control Group 15 9 14 4 8 10 7 6 22 239 6 36 4 19 5 14 18 17 15 9 9